Piston



0; C. KREIS PISTON Nov. 2 1926. v 1,605,040

Filed July 16, 1925 INVENTOR OSCAR c. KREIS ymwm AT TORNEY Patented Nov. 2, 1926.

UNITED STATES PATENT OFFICE.v

OSCAR c. Runs, on nn'rnorr, MICHIGAN, ASSIGNOB, TO CONTINENTAL Moronsoom PORATION, or DETROIT, MICHIGAN, A. coRronA'rIon or VIRGINIA.

rIszron.

Application filed July 16, 1925. Serial No. 43,937.

My invention relates to an improved construction of piston for internal combustion motors, constructed .to remove excess oil from the cylinder wall and prevent oil pumping without the accompaniment of undesirable noises heretofore experienced with certain types of structure intended for the purposes of preventing oil pumping.

In connection with solving the problem of preventing oil pumping and removing surplus lubricating oil from the cylinder walls of a motor, it has been found that the lowermost piston ring is quite efiiective inremoving the oil from the cylinder wall and that the problem is largely one of taking care of the oil after it is removed by the ring, so that the surplus oil will not again be applied to the cylinder wall. Removing this surplus oil ha heretofore been taken care of by drainage holes from some part of the lowermost ring groove, through the piston wall to'its interior so that the surplus oil removed by the lowermost ring finds its way through the piston wall and into the crank case of the motor, without again coming directly into contact with the cylinder wall. In removing the surplus oil from the cylinder wall as described, it has been found effective to employ a piston ring 1 having openings extending radially through has been found that 1t, either by slotting the-ring par'allelwith the end walls of the ring or drilling radial holes through the ring closely together. It rings of this kind are much more effective in removing surplus oil from the cylinder wall than are plain rings. On account of the openings through the rings however, the surplus oil removed by the ring rapidly accumulates in the bottom of the ring. groove, from' which it has heretofore been drained through the piston wall as described. While the construction described has served to remove the surplus oil from the cylinder wall in a more or less satisfactory manner depending upon the particular construction. it has been found that undesirable noises invariably accompany the operation of themotor provided with pistons constructed as just described,

due probably to the split piston ring lying in the path of flow from the slight clearance between the piston and the cylinder through the ring groove and through the drainage holes from the ring groove to the interiorof the piston; during each firing stroke, sufficient leakage occurs past the upper rings of the piston due to the high pressures then produced, so that an appreciable flow I of fluid consisting partly of burned mixture" and partly of lubricating oil is forced through the path of the flow just referred to, which path also may be between the up-' a reed, and the result. is the production of a high pitched shrill sound for each firing or power stroke of the piston. The undesirable result described is due of course to the great difference of pressure between the slight clearance around the piston and the inside of the piston, which sets up a high velocity flow of the fluid through the path described. I

By my invention 1 obviate the undesirable results described, by providing two sets of drainage holes, the first set extending from the bottom of the lowermost ring groove of the piston downwardly and outwardly so they open on the outer surface of the piston a short distance below the lower edge of the lowermost ring groove. This first set of drainage holes servesto keep the ring groove inside of the ring free from an excess of oil, thus permitting the piston ring to function in removing the surplus oil from the cylinder wall, but as the ends of this first set of drainage holes are subjected to substantially the same pressure during a firing or power stroke, or at most the difference of pressure is not great, the velocity of fluid flow past the ring or through it is not great enough to set up the undesirable noises referred to. I also provide a second set of drainage holes from the outer surface of the piston below the lowermost ring groove, to the interior of the piston, this second set of holes serving to collect and drain the surplus'oil delivered from the first set of holes so that the major part of this oil is drained through the piston to its interior,

and thus finds its way to the crank case. I find that the combined action of the two sets of drainage holes mentioned, eflect'ively removes the surplus oil and that the action is quiet as far as the undesirablenoises referred to are concerned, the pressures exerted on the outer ends of the second set of holes being relatively small and furthermore the fluid flow through the second set of drainage holes being entirely separate from the lower piston ring.

My invention will best be understood by reference to the accompanying .drawings showing a preferred embodiment thereof in whicha Fig. 1 is a vertical central sectional view through a piston constructed in accordance with my invention,

Fig. 2 is a sectional view of the construction shown in Fig. 1 taken along the line 22,

Fig. 3 is a sectional view to an'enlarged scale, of the construction shown in Fig. 2 taken along the line 33,

Fig. 4is a sectional view to an enlarged scale, of the construction shown in Fig. 2 taken along the line 4-4, and

Fig. 5 shows in a view similar to Figs. 3 and 4 a construction commonly heretofore used. v 1

Similar numerals refer to similar parts throughout the several views.

As shown in Figs. land 2 my improved piston 10 is generally of a form commonly used in the art, and is provided with a plurality of ring grooves 11, 12, 13 containing piston rings 14, 15, 16 respectively, said piston being also provided with supports, 17, 18 for a piston pin. The rings 14, 15, and 16 illustrated are of the type having openings 14 15 16 extending radially through them, either by slotting the rings or forming radial holes through them, the particular construction of the piston rings not being an essential part of my present invention,

and these rings being referred to as having openings through them only because rings of this kind are found to operate somewhat more eflectively in removing surplus oil from the piston walls than are rings of solid cross section.

As indicated in Figs. 1 and 2 I form a first set of drainage holes 19 from the bottom of the groove 13 so that they extend downwardly and outwardly to the outer surface of the piston a short distance below the groove 13, as more clearly shown in Fig. 3. Intermediate the holes 19 I form a sec- 0nd set of drainage holes 20 through the piston each of said holes, as indicated in Fig. 4, extending from the outer surface of the piston immediately below the groove 13 downwardly and inwardly to the interior of the piston. The holes 19 effectively drain the oil collected in the bottom of the groove 13 to theouter surface of the piston below the outer ends of the holes 20 so that the surplus lubricating oil delivered from the holes 19 cannot again reach the ring 16 without passing the outer ends of the holes 20. Immediately below the groove 13 and in the outer surface of the piston I preferably form a small annular recess 21, partly to facilitate the drilling of the holes 20 and partly to receive the surplus oil delivered from the holes 19, this recess 21 serving to collect the surplus oil and communicate it to the holes 20, by which it is drained to the interior of the piston.

From the construction described, it will appear that any fluid pressure produced on the ring 16 during a power stroke of the piston, whether on the upper surface of the ring or on its outer surface, cannot result in a high velocity flow of fluid through the holes 19, on account of the delivery ends of these holes being in close proximity to the cylinder wall and not having a free and uninterrupted discharge. The clearance between the piston and the cylinder wall is sufficient however so that the lubricating 'oil collected in the bottom of the groove 13 is effectively drained through the holes 19 from the groove It will also be observed that the part of the surplus lubricating oil that finds its way upwardly from the d is-' charge ends of the holes 19, is collected in the recess 21 and from said recess flows without restriction through the holes 20 to the interior of the piston. There is thus no path'of free flow between the holes 19 and the holes 20; at the same time the'flow is permitted to a sufficient extent to effectively drain the groove 13, and since the holes 20 are entirely below the ring 16 and have no communication whatever with the bottom of the groove 13, a high velocityof flow is not produced in the holes 20' and there is no tendency to set up whistling noises by the flow of either lubricating oil or leakage age holes.

from the inlet ends of the holes 20, effects a distribution of the fluid flow so as to permit quiet action of the drainage and check and prevent rapid flow through said holes of any gases that may find their way by leakage into the groove 13.

In Fig. 5 I illustrate a type of piston construction heretofore employed for draining surplus lubricating oil to the interior of the piston, in which the piston wall 10 has formed through it drainage holes 22 from its interior to the inner portion of the lowermost ring groove 13 a piston ring 16 be ing illustrated in said groove, said ring being of the same general construction as the ring 16 and having openings 16 extending radially through it. With this construction, it will be observed that there is direct communication through the holes 22 tween the inner surface of the ring and the bottom of its groove. With this construction-the efi'ect is to remove the surplus oil by means of the ring 16 from the cylinder wall -and communicate it to the bottom of the ring groove 13. During a power stroke of the iston the gases from the cylinder,

' which a ways leak past the rings to a greater orv less extent, find their way through the clearance between the ring and its groove or through the ring, to the bottom of the groove and thus any pressure that may be exerted on the leakage gases is communicated directly to the outer ends of the holes 22 and a relatively uninterrupted path is provided for fluid flow from the outer surface of the piston around and through the piston ring to the interior of the piston, where the pressure is substantially equal to atmos pheric pressure at all times. This piston ring 16 is thus directly in the path of this high velocity fluid fldw at all times and the high velocity flow has a pronounced tendency to cause the split ends of the ring to vibrate like a reedproducing undesirable high pitched shrill sounds during the high velocity flow; These undesirable results are overcome by my improved construction in the manner described, with the result that 'my improved iston is quiet in action, that the surplus lu ricating oil is moved effec-- tively, and that the quantity of leakage from the cylinder is a minimum.

While I have shown In invention in the particular embodiment a ove described, it

will be understood that I do not limit myself to this exact construction as I may employ equivalents known to the art at the time of the filing of this application without departing from the scope of the appended claim.

What I claim is:

A piston for internal combustion motors having a head and a cylindrical wall having ring grooves containing piston rings characterized by providing the cylindrical wall with a first set of oil drainage holes from the bottom of the lowermost ring groove to the outer surface of said wall below said ring groove, and a second set of oil drainage holes through said wall-from the piston.

In witness whereof, I hereunto subscribe iny name this 6th day of July, A.. D1925.

' OSCAR C, KREIS.

the" outer surface thereof to the interior of 

